I was born with two middle names, one beginning with an A and the second one beginning with a P. When only one middle initial is allowed, like on most forms, my initials would spell R.A.T. On many early legal forms, like my USA citizenship naturlization papers, only the A is listed.
As a young kid in elementary school I did not, of course, like the RAT thing, so when I was around 12 or so I said screw it, I’m just going to drop A and only use P. So everywhere I went or signed up for, I used only P. At 16, driver’s license, and that worked. When I joined the Marines at 19, same thing. And when I got my passport later, too.
I have never looked back. This is not a big deal because it’s a change only in middle name, and yet A and P are on my birth certificate so I could always point to that if I had to.
But it’s been 40 years so far. I’ll take P with me to my grave.